Heating and ventilating apparatus



Nov. 9, 1948. H. A. PlETscl-l HEATING AND VENTILATING APPARATUS 4 Shets-Sheet l Filed May 12, 1942 w q Q A ATTORNEYS Nov. Q, 1948. H. A. FuErscl-lg 2,453,382

` HEATING AND VENTILATING APPARATUS Filed Mayy l2, 1942 4 Sheets-Sheet 2 w )d elfo: QH I H g1g a s ATTORNEYS Nov. 9, 1948. H. A. PlETscH HEATING AND VENTILATING APPARATUS 4 sheets-sheet s Filed May 12, 1942 ATTORNEYS 7, INXEFLITOR s;

H. A. PIETSCH HEATING AND VENTILATING APPARATUS Nov. 9, 1948.

4 SheetS-Sheet 4 Filed May l2, 1942 TRODE Z0 lNvENToR 7m a. fw BY Y ATTORNEYS Patented Nov. 9, 1948 HEATING AND VEN TILTING APPARATUS Herman A. Pietsch, Greeri'tree,` Pa.,y assignor to` Bravo Corporation, Pittsburgh', Para, a. corporation of Pennsylvania Application May 12, 1942, SeralJNo. 442,615

1 claim. 1

This invention relates to ventilation, and consists in apparatus for heating to a uniform and predetermined temperature a stream drawn from the open air where temperature is Variable and unpredictable in value. The invention nds practical application in the ventilation of the chambers and spaces Within buildings and industrial plants, where fumes injurious to equipment or noxious to workmen are generated.

In the accompanying drawings Fig. I is a View in Vertical section of a particular installation of the apparatus of the invention; Fig. II is a View to larger scale, in vertical and transverse section, on'k the plane indicated at II-II, Fig. I. Figs. III and IV are fragmentary views to yet larger scale, on the horizontal planes severally indicated in Fig. II by the lines III-III and IV-IV. Fig. V is a wiring diagram.

In a vertical wall 50, that may be understood to be the outer wall of a building, a window opening is formed, and in the opening is conveniently set a bank 5| of louvre slats. Within the building an air box 52 is mounted. To this box atmospheric air, entering through the window opening, has free access. From the box a conductor 54 leads; and fans 53, arranged within the box, induce now and drive a stream of air through the conduit 5d to the desired place of emergenceinto the room to be ventilated'. Athwart the stream, and, as here shown, at the otherwise open intake end of the air box 52 a skeleton burner 55 extends. The burner is submerged in the stream of air that the fans impel; the air ows around the burner and passes intimately over all its ramifications.

In the sectional View, Fig. I, two fans 53 appear. There are in this installation four fans in all, standing as in Fig. I they are shown to sta-nd. They are grouped in square assembly, and, as seen in Fig. I they stand aligned two by twov in the line of sight.

As best seen in Fig. II. the burner here consists of a plurality of elongate loops 56 of pipe perfo rated throughout all the extent of the loop and on the down-stream side (relatively to air flow) with multitudinous orifices. From these orices flames spring and burn freely in the air stream that ows with little disturbance over the loops. These loops 56 (in this case fourteen in number) are arranged in two banks, symmetrical with respect to the vertical mid plane through the air box. The loops of the two banks are oppositely arranged', pair by pair. The elaborate skeletony or open grdwork burner is functionally sectional, and, section` by section, it may be brought into and taken outy of" operation. The burner is fed 2 through agas supply pipe 5l. Comparing Figs. II and III, itl will be seen that valves I4 set in leads STO from pipe 5'1 control gas now tothe loops, pair by` pair. ThisI is the case with all of thepa'ired loops, excepting only the central pair iIr the succession. These are distinguished in the dra-wingsA by the numerals 560'. With respect to that central1 pair, and as showny in Fig. IV, two valves M are provided, and they are set in the leads to the two loops severally. Thus itv is pos'- sible; by proper control of thevalves I4, to bring into service a single loop of the burner or any multiple of a singlek loop', up to full capacitythat isA to say, inthis case, up tofourteen loops.

The` supply pipe 51 extends vertically and centrally between the two banks oil loops. At the opposite ends of the banks pilot burners 58 are arranged. These pilot burners consistr of ori'fioed lengthsv of pipe that extendI vertically adjacent the: ends of the loops 56. The pilot burners are fed through the branch 59 from the supply pipe 51. Fig. II gives theV structural appearance of the assembly, and shows the pipes 558'- to be structurall'y united to the loops 56. It will, however, be understood that the union' hereVA is structural only; and that there` is ne passageway' for gas between' the pipes 5-8- and the loops5'6`.

Thel burners are refined in structure, as the art knows, to" aii'ord practically complete combustion, with the production of carbon dioxide and water vapor.

In the gas supply line are set (Fig. II) a pressure regulating' valve` 23, a shut-orf valve lil', and a pneumatically operated` control valve lil. The pressure regulating valve 23 is effective, that, under Varying pressure at the source; the gas shall reach the burners at a pressure not exceeding a pre-determined maximum. A ley-pass around the control valve l1 is provided with a pressure-regulating valve 211.A In the branch 59, through which the pilot' burners are fed, are set a pressurel operated switch 6, and' a shut-oli valive 8.

SparkL-plugs 9; 9, assembledv with the essential ignition transformers or' induction coils, areA provided for lighting the pilot burners 58', and fia-me units 20, 2|l are associa-ted', one'- with each spark plug andfits ignition transformers In the entering stream oi coldv air is arranged a remote bulb-tlflermostatr 4` of the mercuryswitchtype. The bul-b is subject to the temperature'v ofthe incoming fresh ai-r. In the on--owing stream or heated airis arranged a thermostat 5l of like character.

A control system is provided that is effective aisance operation consists, rst, in the energizing of the fans, and second, in the openingr of the valve I in the gas supply line. The fans set in motion sweep the air box clean of any accumulation of gas before any other part of the organization comes into action. When the fans have con,- tinued in action for an initial short but sulficient interval of time, a pushbutton maybe pressed that controls further operation. The induction coils ofthe spark-plugs arel than automatically energized; gas is automatically allowed to flow to the pilot burners; land the pilot burners are automatically lighted. When these preliminary operations have occurred the control valve in the main gas supply line is released, so that it may be opened. This valve then is opened manually, and the heater is brought into action. Meanwhile, the ignition transformers, their purpose served, are automatically deenergized. The opening of the control valve in the main supply line causes the loops oi the burner to be lighted from the pilot burners, and, according as the temperature of the entering al1' is high or low, few or many ofy these loops will be brought into play. (4) Asv temperature conditions change, the number of loops that are brought into play increases and diminishes, and, when any number of the loops are active and when conditions are in state of change, so as to bring about increase or diminution of the number of loops in action, the volume ofthe supply of gas to the loops will increase or diminish. Thus, minute gradation is afforded in the increase or decrease of the rate of heat generation. (5) In case gas pressure fails to a dangerous minimum the heater will automatically go out of operation. temperature becomes so warm that heating is unnecessary, the heater will automatically go out of operation. (7) In case the temperature of the delivered air rises to a degree exceeding a predetermined maximum, the heater. will automatically go out of operation. And in any case, when once the heater has gone out of operation, operation can be renewed only through manual intervention.

The control apparatus is advantageously mounted on a panel I6 within a control room Gil. Its parts are shown diagramatically in Fig. V in organization with the heater parts. Electric energy is taken from service line 6I; and pneumatic power is supplied at 62. In Fig. V the electric circuits are indicated in full lines; the pneumatic connections in heavy dotted lines.

Operation, of which a summary has already been given, is now repeated in detail, and .with reference to the drawings-particularly to Fig. V.

The fans are set in operation by the manual shifting of the switches I8. The shifting of the switches elects the closing of the corresponding contacts of relays 2. This particular installation is so arranged that it is onlyin ,sequenceI upon (6) In case the out-of-doorsy the operation of at least two of the fans that the heater can be brought into operation, and to such end the relay contacts are wired, as indicated in the diagram. When at least two of the fans have continued in operation for a predetermined time interval, in this case three minutes, the purge timer 3 becomes effective. The purge timer is a delayed action switch. Several types are available on the market, and the one here employed includes a resistance element that is slowly distorted under the effect of an electric current, and that is, after a predetermined interval of time, effective to close the switch contacts. The push button I may then be pressed with effect.

When the push-button I is pressed circuit is completed through relays 7, 1, to the solenoid that controls valve 8 in the branch line 59 that supplies gas to the pilot burners, and to the induction coils or ignition transformers of spark-plugs 9, 9. Thereupon the pilot burners are lighted. Flames projected by the pilot burners play upon the two electrodes 20, 2|, and in so doing oomplete circuits that energize additional ,units within relays 'I, 1. These units, so energized,

are effective, both to break the circuits through A I which the coils of the spark-plugs, 9 have been energized (so that the spark plugs now go out of action), and to complete a circuit that effects the shifting of a latch upon valve Ill, releasing the valve `to respond to manual operation. The relays l, l, spark-plugs 9, 9, and electrodes 2D, 2l form the essential elements of a known -piece of apparatus that is supplied by- The Brown Instrument Company of Philadelphia', Pennsylvania' under the trade name Brown Protectoglo.

Pneumatic pressure, entering at 62, has access,

`through controller I2 and electrically operated pneumatic switch H, to switches I3. Maximum pressure exerted upon switches I3 closes all circuits and opens all valves I and maximum pressure effects the opening to the full of valve I'I also.

When valve IB is opened the burner lights itself from the already lighted pilots; and as the burner continues in operation the air in the fan impelled stream is heated. The thermostat bulbL 12a in the line of stream now responds -to thc rising temperature, and effects a corresponding response in an air Valve in controller I2.

rIhe controller I2 is an instrument known to the art, available under the trade name Air-O- line Potentiometer Controller from The Brown Instrument Company, above mentioned. Suifice it to say that the pneumatic pressure in the air line extending from the controller is temperature governed; that the controller is so organized as to afford to the switches I3 pneumatic pressure that ranges from zero to fifteen pounds. The actual value depends upon and accords with the temperature of the stream of heated air that flows from the burner. At zero pressure the control valve if! is closed, all the pneumaticelectric switches E3 are cle-energized, and all the lsolenoid valves I 4 are closed; at a pressure of varies, particular valves I4 Will open and close,

so as to alford correspondingly varying volumes of flame in the burner.

The degree of opening of valve I'I is in general v and valve Il has this further value Iand effec-t, that it corrects or graduates what otherwise would be a step-by-step augmentation and diminution in :the quantity of heat units released at lthe burner. As the pressure changes, causing increase or diminution inthe number of burner loops currently active, the simultaneous shifting of valve I1, increasing or decreasing the gas flow, makes compensation, prevents the step--by-step effect alluded to, and affords instead an evenly graduated augmentation or diminution in the heat release.

The thermostat 5 includes a mercury switch. When the maximum predetermined temperature has been attained, this switch, normally closed, is opened. The opening of the switch in element 5 effects the opening of `the circuit of the electrically operated pneumatic switch II. When this circuit is opened the air line is bled, pressure fails in the pneumatic line, all the switches I3 are deenergized, all the valves I4 close, and valve I'I closes.

Similarly when the temperature of the outside air rises toa degree at which heating is unnecessary and undesired the thermostat 4 is effective to close all valves I 4 and the valve I1 also.`

When the pressure of the gas supply fails and reaches a critical minimum, the pressure switch 6 (here conveniently arranged in the branch line 59) opens a circuit with the same effect-the operation cf switch II, and the consequent loss of pneumatic pressure and the closing of all valves.

Fig. V shows the three switch members 4, 5, and 6 to be included in series in a single circuit. All three switches are normally closed. The opening of any one results in the opening of the circuit of switch II.

Failure of the flame of either of the pilot burners breaks .a flame circuit through the corresponding relay 1. In consequence, all circuits are opened, both of the valves 8 and I0 close, Valve I1 closes, and all the valv-es I4 close.

When .the valves have closed the fans will continue in operation until their switches I8 are man ually shifted.

I claim as my invention:

In a direct-nred heater system where gas fuel is burned in a duct through which air to be heated is circulated, the combination with a duct and means for circulating a current of air through the duct. of a plurality of gas burners in the duct, a comm-on gas supply line and manifold for all yof the burners, a modulating valve means in the supply line operable to gradually increase and diminish the supply of gas to :the burners, a separate valve between each burner `and the manifold for individually 4controlling each burner, means for progressively opening or closing the last-named valves -in predetermined order to selectively vary the number of burners in operation, and means for operating the modulating valve to gradually increase or diminish the supply of gas to the burners then in operation whereby ythe temperature of lthe air being heated may .be modified through a substantially uniform gradient as burners are progressively rendered operative or inoperative.

HERMAN A. PIE'DSCH.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,819,560 Klees Aug. 18, 1931 1,938,625 Engles Dec. 12, 1933 2,081,091 Kuempel May 18, 1937 2,119,153 Dallenbach May 31, 1938 2,139,344 Anders-on Dec. 6, 1938 2,194,713 Mitchell Mar. 26, 1940 2,300,560 Faber Nov. 3, 1942 2,311,710 Thomas Feb. 23, 1943 

